# -*- coding: utf-8 -*-
from django.conf import settings


DATABASE_MAPPING = settings.DATABASE_APPS_MAPPING

class DatabaseAppsRouter(object):
	"""
	A router to control all database operations on models for different
	databases.

	In case an app is not set in settings.DATABASE_APPS_MAPPING, the router
	will fallback to the `default` database.

	Settings example:

	DATABASE_APPS_MAPPING = {'app1': 'db1', 'app2': 'db2'}
	"""

	def db_for_read(self, model, **hints):
		""""Point all read operations to the specific database."""
		if model._meta.app_label in DATABASE_MAPPING:
			return DATABASE_MAPPING[model._meta.app_label]
		return None

	def db_for_write(self, model, **hints):
		"""Point all write operations to the specific database."""
		if model._meta.app_label in DATABASE_MAPPING:
			return DATABASE_MAPPING[model._meta.app_label]
		return None

	def allow_relation(self, obj1, obj2, **hints):
		"""Allow any relation between apps that use the same database."""
		db_obj1 = DATABASE_MAPPING.get(obj1._meta.app_label)
		db_obj2 = DATABASE_MAPPING.get(obj2._meta.app_label)
		if db_obj1 and db_obj2:
			if db_obj1 == db_obj2:
				return True
			else:
				return False
		return None

	# for Django 1.4 - Django 1.6
	def allow_syncdb(self, db, model):
		"""Make sure that apps only appear in the related database."""

		if db in DATABASE_MAPPING.values():
			return DATABASE_MAPPING.get(model._meta.app_label) == db
		elif model._meta.app_label in DATABASE_MAPPING:
			return False
		return None

	# Django 1.7 - Django 1.11
	def allow_migrate(self, db, app_label, model_name=None, **hints):
		print db, app_label, model_name, hints
		if db in DATABASE_MAPPING.values():
			return DATABASE_MAPPING.get(app_label) == db
		elif app_label in DATABASE_MAPPING:
			return False
		return None
